This invention relates to silicone release coating compositions. More particularly, this invention relates to a silicone release coating composition that has excellent bath stability, that forms a very stable thin film on applicator rolls, that cures rapidly even at relatively low temperatures, that exhibits stable curing characteristics during the course of bath aging, and that also provides stable cured-film release values during the course of bath aging.
Organopolysiloxane compositions that cure by addition reaction to give release films are known. For example, Japanese Patent Application Laid Open No. 61-261 (261/1986) discloses a silicone release coating composition comprising an organopolysiloxane having at least 2 vinyl groups in each molecule, an organopolysiloxane having at least 2 silicon-bonded hydrogen atoms in each molecule, an organosilane compound containing 1 or 2 C.tbd.C functional hydrocarbon groups bonded across oxygen to silicon, and a platinum compound. In Japanese Patent Application Laid Open No. 64-51466 (51,466/1989) is disclosed a silicone release coating composition comprising an organopolysiloxane having at least 2 vinyl groups in each molecule, an organopolysiloxane having at least 2 silicon-bonded hydrogen atoms in each molecule, an organopolysiloxane bearing at least 1 C.tbd.C-functional hydrocarbon group bonded across oxygen to silicon, and a platinum compound. IN Japanese Patent Application Laid Open No. 8-176448 (176,448/1996) is disclosed a silicone release coating composition comprising an organopolysiloxane having at least 2 vinyl groups in each molecule, an organopolysiloxane having at least 2 silicon-bonded hydrogen atoms in each molecule, a C.tbd.C-functional compound having a boiling point at ambient pressure of at least 150.degree. C., a C.tbd.C-functional compound having a boiling point at ambient pressure less than 150.degree. C., and a platinum compound.
These silicone release coating compositions unfortunately suffer from a number of problems. They have unsatisfactory bath stability and unsatisfactory stability when formed into a thin film on an applicator roll. Moreover, improvements in these stabilities lead to an inability to cure the composition rapidly at relatively low temperatures. These silicone release coating compositions also suffer from such problems as a decline in curability during the course of bath aging and changes in the cured-film release values during the course of bath aging.